On a size exclusion separation column (e.g. Sephadex) would you expect the longer or shorter chain length compound to be eluted first? Why? Explain?
Thanx!
On a size exclusion separation column, the longer chain length compound would be eluted first, while the shorter chain length compound would be eluted later. This is because the separation column is designed to separate compounds based on their size and molecular weight.
Size exclusion chromatography works by utilizing porous beads or gels in the separation column. These beads or gels have different pore sizes, which allow molecules to enter the pores based on their size. Larger molecules will be excluded from entering the pores and will pass around the beads, resulting in a shorter retention time. On the other hand, smaller molecules can effectively enter the pores and will have a longer retention time.
Longer chain length compounds, such as polymers or macromolecules, have a larger size due to their extended structure. When injected into the size exclusion separation column, these longer compounds cannot penetrate the pores and are excluded, leading to their earlier elution. In contrast, shorter chain length compounds can easily enter the pores and take longer to pass through the column, resulting in their later elution.
To determine which compound would be eluted first on a specific size exclusion separation column, you would need to consider the molecular weights and sizes of the compounds you are analyzing. This information can be obtained through methods such as gel permeation chromatography or through known literature values for the compounds you are studying.